Comcast says DOCSIS 3.1 is ready

On Tuesday, Comcast officially announced to the world that it is now ready to deploy DOCSIS 3.1 powered ultra high-speed gigabit cable Internet service to five major metropolitan markets in the United States during 2016, making it the first time consumers can receive gigabit speeds over the company’s hybrid fiber coaxial (HFC) network.

The company will offer DOCSIS 3.1-powered gigabit cable service to Atlanta and Nashville in early 2016, while Chicago, Detroit and Miami will follow in the second half of the year. The announcement follows a DOCSIS 3.1 modem test that Comcast conducted in Philadelphia in December 2015. Back then, the company unveiled that it was activating several more “test homes” in Pennsylvania, Northern California and Atlanta.

“The beauty of DOCSIS 3.1 is that it is backwards compatible, so no digging up streets or backyards,” said Comcast Executive VP and CTO Tony Werner.

Last winter during CES 2015 in Las Vegas, Broadcom was the first to show off a DOCSIS 3.1-based SoC for cable operators, the BCM3390. However, Werner said the company would not be buying Broadcom's solution. Then during May 2015, Comcast previewed its D3.1-based “Gigabit Home Gateway” devices during INTX in Chicago. It said the device was expected to go into production in the second half of 2015, and that Arris and Taiwan’s Compal Electronics would be the company's manufacturing partners involved in the D3.1-based devices. The units also include support for Reference Design Kit B (RDK-B).

Comcast's DOCSIS 3.1-ready gateway modems, as shown during INTX 2015

The DOCSIS 3.1 standard was first released in 2013 and supports capacities up to 10Gbps downstream and 1Gbps upstream using 4096 QAM (quadrature amplitude modulation). The new standard uses smaller 20KHz to 50KHz wide OFDM (orthogonal frequency-division multiplexing) subcarriers that can be bonded together for up to 200MHz bandwidth. Thankfully, DOCSIS 3.1 also uses a new DOCSIS-PIE (Proportional Integral Controller Enhanced) algorithm to reduce “bufferbloat,” a term used to describe excess packet buffering resulting in higher latency, jitter, and reduced overall network throughput. In fact, DOCSIS-PIE is a mandatory part of DOCSIS 3.1, according to the IEEE.

"We’re constantly working to ensure that our customers get the fastest speeds available, and that they get them first," said Comcast Central Division President, Bill Connors. "DOCSIS 3.1 represents a tremendous step forward in our commitment to keeping customers at the technology forefront. Combined with all the upgrades we have already put into our advanced fiber optic-coax network, this technology will not only provide more gigabit speed choices for customers, it will also eventually make these ultra-fast speeds available to the most homes in our service areas."

Image credit: GigaOm

The company already offers XFinity 2Gbps symmetrical fiber service for $299.95/month in over 123 cities and regions, reaching 18 million households nationwide. This service was deployed using a national fiber backbone that has taken Comcast the past decade to build across 145,000 route miles of fiber. However, the Xfinity Gigabit Pro 2Gbps is only available to those within close proximity of the company’s fiber network.

Comcast Fiber Network (December 2015)

"Because the new [HFC] network technology allows consumers to receive gigabit internet speeds over an existing connection, it has the potential to make ultra-fast speeds available more widely than fiber-to-the-home services, which typically require new construction and specialized installations," Comcast says.

When fully deployed, Comcast expects its hybrid fiber coaxial (HFC) service to reach every customer in its footprint and be able to receive at least gigabit speeds over its existing network (through a combination of fiber and coaxial lines).